Food legumes are the main source of dietary protein for a large part of the world's population, and also play an important role in maintaining soil fertility through nitrogen fixation. However, legume yields and production are often limited by large genotype×environment (G×E) interactions that influence the expression of agronomically important, complex quantitative traits. Consequently, genetic improvement has been slower than expected. Molecular marker technology enables genetic dissection of such complex traits, allowing breeders to identify genomic regions on the chromosome that have main effects or interactive effects. A number of genomic resources have been developed in several legume species during the last two decades, and provide a platform for exploiting marker technology. The present paper reviews the available genomic resources in food legumes: linkage maps, high-throughput sequencing technologies, expression sequence tag (EST) databases, genome sequences, DNA chips, targeting induced local lesions in genomes (TILLING), bacterial artificial chromosome (BAC) libraries and others. It also describes how these resources are being used to tag and map genes/quantitative trait loci (QTLs) for domesticated and other agronomically important traits. This information is important to genetic improvement efforts aiming at improving food and nutrition security worldwide.

Global climate change is predicted to shift seasonal temperature and precipitation patterns. An increasing frequency of extreme weather events such as heat waves and prolonged droughts is predicted, but there are high levels of uncertainty about the nature of local changes. Crop adaptation will be important in reducing potential damage to agriculture. Crop diversity may enhance resilience to climate variability and changes that are difficult to predict. Therefore, there has to be sufficient diversity within the set of available cultivars in response to weather parameters critical for yield formation. To determine the scale of such ‘weather response diversity’ within barley (Hordeum vulgare L.), an important crop in northern conditions, the yield responses of a wide range of modern and historical varieties were analysed according to a well-defined set of critical agro-meteorological variables. The Finnish long-term dataset of MTT Official Variety Trials was used together with historical weather records of the Finnish Meteorological Institute. The foci of the analysis were firstly to describe the general response of barley to different weather conditions and secondly to reveal the diversity among varieties in the sensitivity to each weather variable. It was established that barley yields were frequently reduced by drought or excessive rain early in the season, by high temperatures at around heading, and by accelerated temperature sum accumulation rates during periods 2 weeks before heading and between heading and yellow ripeness. Low temperatures early in the season increased yields, but frost during the first 4 weeks after sowing had no effect. After canopy establishment, higher precipitation on average resulted in higher yields. In a cultivar-specific analysis, it was found that there were differences in responses to all but three of the studied climatic variables: waterlogging and drought early in the season and temperature sum accumulation rate before heading. The results suggest that low temperatures early in the season, delayed sowing, rain 3–7 weeks after sowing, a temperature change 3–4 weeks after sowing, a high temperature sum accumulation rate from heading to yellow ripeness and high temperatures (⩾25°C) at around heading could mostly be addressed by exploiting the traits found in the range of varieties included in the present study. However, new technology and novel genetic material are needed to enable crops to withstand periods of excessive rain or drought early in the season and to enhance performance under increased temperature sum accumulation rates prior to heading.

The main objective of the present crop simulation study was to determine the impact of climate change on the winter wheat production of a dry area situated in north-east Austria (Marchfeld region) based on the CERES-Wheat crop-growth simulation model associated with global circulation models (GCMs). The effects of some of the feasible regional- and farm-based adaptation measures (management options) on crop yield and water and nitrogen (N) balance under the climate scenarios were simulated. Climate scenarios were defined based on the ECHAM5, HadCM3 and NCAR PCM GCM simulations for future conditions (2021–50) as described in the Special Report on Emission Scenarios A1B (Nakicenovic & Swart 2000). The potential development, yield, water demand and soil N leaching were estimated for winter wheat and all of the defined climates (including rising CO2 levels) and management scenarios (soil cultivation, windbreaks and irrigation).

The results showed that a warming of 2°C in the air temperature would shorten the crop-growing period by up to 20 days and would decrease the potential winter wheat yield on nearly all of the soil types in the region. Particularly, high-yield reductions were projected for light-textured soils such as Parachernozems. A change from ploughing to minimum tillage within the future scenario would lead to an increase of up to 8% of the mean yield of winter wheat. This effect mainly resulted from improved water supply to the crop, associated with higher soil water storage capacity and decrease of unproductive water losses. Hedgerows, which reduce the wind speed, were predicted to have particularly positive effects on medium and moderately fine-textured soils such as Chernozems and Fluvisols. With both management changes, regional mean-yield level can be expected to be +4% in comparison with no management changes in the future conditions. Compared with the baseline period, water demand for the potential yield of winter wheat would require 6–37 mm more water per crop season (area-weighted average). The highest water demand would be on medium-textured soils, which make up the largest amount of area in the study region. Additionally, the effects of snow accumulation near hedgerows would further increase the yield, but would also lead to higher N leaching rates. However, specific management options, such as minimum tillage and hedgerows, could contribute towards reducing the increasing water demand.

Four field experiments were conducted over 3 years to study whether adding a strobilurin fungicide to a triazole fungicide programme for disease control in winter wheat had any influence, in combination with different rates of fertilizer nitrogen (N), on the severity of foliar diseases, the degree of leaf senescence and consequently on yield. Septoria tritici was the dominant foliar disease observed in all experiments. The area under the disease progress curve (AUDPC) tended to be greater for untreated plots than those treated with fungicides; however, the performance of the programme containing a strobilurin fungicide did not always exceed that of the triazole-only programme. Fitting a quadratic equation to relationships between leaf N concentration and the proportion of leaf area covered with S. tritici on a relative scale across the four experiments indicated a possibility that there could be an optimum N concentration in host plants for S. tritici to develop, rather than a simple increase or decrease with a rise in plant N concentration. Plant height tended to be reduced following an application of a mixture of epoxiconazole and trifloxystrobin; however, it was not clear whether there was any association between plant height and the severity of S. tritici. S. tritici caused a reduction in mean grain weight (MGW) in most of the experiments. It was concluded that an optimum leaf N concentration may exist for S. tritici in winter wheat.

On-farm yield experiments were carried out in the Tombouctou region of Mali in 2009/10 under heat- and drought-prone desert conditions with three local landraces of seed-type watermelons. The landraces, named Fombou, Kaneye and Musa Musa by the farmers, exhibited distinct characteristics for fruit morphology, but in particular for seed traits. On average, the three landraces produced a fruit yield of 11·6 t/ha and an estimated seed yield of 364 kg/ha, with no significant differences among landraces. Kaneye showed the highest stability of fruit number/ha in different field environments, suggesting this landrace is the best among the three for a poor growing environment, whereas Fombou and especially Musa Musa responded positively to more favourable environments. Seed weight revealed a different trend, with Fombou as the most responsive to favourable conditions, while Kaneye and Musa Musa were less responsive. The yields obtained suggest that these local landraces of watermelon are valuable plant genetic resources for securing food supply in arid, heat- and drought-prone areas.

Multipurpose legumes provide a wide range of benefits to smallholder production systems in the tropics. The degree of system improvement after legume introduction depends largely on legume biomass production, which in turn depends on the legumes’ adaptation to environmental conditions. For Canavalia brasiliensis (canavalia), an herbaceous legume that has been recently introduced in the Nicaraguan hillsides, different approaches were tested to define the biophysical factors limiting biomass production on-farm, by combining information from topsoil chemical and physical properties, topography and soil profiles.

Canavalia was planted in rotation with maize during two successive years on 72 plots distributed over six farms and at contrasting landscape positions. Above-ground biomass production was similar for both years and varied from 448 to 5357 kg/ha, with an average of 2117 kg/ha. Topsoil properties, mainly mineral nitrogen (N; ranging 25–142 mg/kg), total N (Ntot; 415–2967 mg/kg), soil organic carbon (SOC; 3–38 g/kg) and pH (5·3–7·1), significantly affected canavalia biomass production but explained only 0·45 of the variation. Topography alone explained 0·32 of the variation in canavalia biomass production. According to soil profiles descriptions, the best production was obtained on profiles with a root aggregation index close to randomness, i.e. with no major obstacles for root growth. When information from topsoil properties, topography and soil profiles was combined through a stepwise multiple regression, the model explained 0·61 of the variation in canavalia biomass (P < 0·001) and included soil depth (0·5–1·70 m), slope position, amount of clay (19–696 kg/m2) and stones (7–727 kg/m2) in the whole profile, and SOC and N content in the topsoil. The linkages between topsoil properties, topography and soil profiles were further evaluated through a principal component analysis (PCA) to define the best landscape position for canavalia cultivation.

The three data sets generated and used in the present study were found to be complementary. The profile description demonstrated that studies documenting heterogeneity in soil fertility should also consider deeper soil layers, especially for deep-rooted plants such as canavalia. The combination of chemical and physical soil properties with soil profile and topographic properties resulted in a holistic understanding of soil fertility heterogeneity and shows that a landscape perspective must be considered when assessing the expected benefits from multipurpose legumes in hillside environments.

Four field experiments were conducted on wheat, using the bread-making cultivar Hereward, over 3 years to study the interactions between nitrogen (N) and strobilurin fungicides with respect to yield and grain N. In one of the field experiments, above-ground dry matter (DM) yield was greater when the plots were treated with a mixture of triazole and strobilurin than when either no fungicide or triazole alone was applied. On plots that received no N fertilizer, above-ground DM and grain yield were lower for the plots treated with fungicides than for plots not treated with fungicide, which implied that the benefit of applying fungicides could only be exploited with N fertilization. There was no difference in above-ground N accumulation between fungicide programmes; however, greater N accumulation in grains was observed following the application of a mixture of triazole and the strobilurin trifloxystrobin compared with plots treated with either no fungicide or triazole alone. This increase in grain N appeared to be attributable more to improved translocation of N to grains rather than to increased N uptake from the soil. The two strobilurin fungicide ingredients kresoxim-methyl and trifloxystrobin, each mixed with a triazole and tested in the present study, performed differently. Better performance, especially with respect to grain N yield, was observed most frequently with trifloxystrobin compared to kresoxim-methyl.

Near isogenic lines (NILs) varying for alleles for reduced height (Rht) and photoperiod insensitivity (Ppd-D1a) in a cvar Mercia background (rht (tall), Rht-B1b, Rht-D1b, Rht-B1c, Rht8c+Ppd-D1a, Rht-D1c, Rht12) were compared at a field site in Berkshire, UK, but within different systems (‘organic’, O, in 2005/06, 2006/07 and 2007/08 growing seasons v. ‘conventional’, C, in 2005/06, 2006/07, 2007/08 and 2008/09). In 2007 and 2008, further NILs (rht (tall), Rht-B1b, Rht-D1b, Rht-B1c, Rht-B1b+Rht-D1b, Rht-D1b+Rht-B1c) in both Maris Huntsman and Maris Widgeon backgrounds were added. The contrasting systems allowed NILs to be tested in diverse rotational and agronomic, but commercially relevant, contexts, particularly with regard to the assumed temporal distribution of nitrogen availability, and competition from weeds.

For grain, nitrogen-use efficiency (NUE; grain dry matter (DM) yield/available N; where available N=fertilizer N+soil mineral N), recovery of N in the grain (grain N yield/available N), N utilization efficiency to produce grain (NUtEg; grain DM yield/above-ground crop N yield), N harvest index (grain N yield/above-ground crop N yield) and dry matter harvest index (DMHI; grain DM yield/above-ground crop DM yield) all peaked at final crop heights of 800–950 mm. Maximum NUE occurred at greater crop heights in the organic system than in the conventional system, such that even adding just a semi-dwarfing allele (Rht-D1b) to the shortest background, Mercia, reduced NUE in the organic system. The mechanism of dwarfing (gibberellin sensitive or insensitive) made little difference to the relationship between NUE and its components with crop height.

For above-ground biomass: dwarfing alleles had a greater effect on DM accumulation compared with N accumulation such that all dwarfing alleles could reduce nitrogen utilization efficiency (NUtE; crop DM yield/crop N yield). This was particularly evident at anthesis in the conventional system when there was no significant penalty for severe dwarfism for N accumulation, despite a 3-tonne (t)/ha reduction in biomass compared to the tallest lines. Differences between genotypes for recovery of N in the grain were thus mostly a function of net N uptake after anthesis rather than of remobilized N. This effect was compounded as dwarfing, except when coupled with Ppd-D1a, was associated with delayed anthesis. In the organic experiments there was greater reliance on N accumulated before anthesis, and genotype effects on NUE were confounded with effects on N accumulated by weeds, which was negatively associated with crop height. Optimum height for maximizing wheat NUE and its components, as manipulated by Rht alleles, thus depend on growing system, and crop utilization (i.e. biomass or grain production).

Estimates of uncertainties are essential when comparing the greenhouse gas (GHG) emissions from a variety of sources. Monte Carlo Simulation (MCS) was applied to estimate the uncertainties in methane emissions and the methane emission intensities from livestock in Canada, calculated using the Intergovernmental Panel on Climate Change (IPCC) methodology. National methane emissions from enteric fermentation and manure management in 2008 were 21·2 and 4·3 Teragram CO2 equivalents (Tg CO2e) with uncertainties of 38 and 73%, respectively. The methane emission intensities (kg of CO2e per kg of live animal weight) were 5·9, 0·9 and 4·9 from Canadian beef, swine and lamb, respectively, with overall uncertainties of 44, 99 and 101%, defined as the 95% confidence interval relative to the mean. A sensitivity analysis demonstrated that IPCC default parameters such as the methane conversion rate (Ym), the coefficient for calculating net energy for maintenance (Cfi) and the methane conversion factor (MCF) were the greatest sources of uncertainty. Canadian agricultural methane emissions are usually calculated by province and by animal subcategories. However, the IPCC default parameters can be assumed to be correlated among regions and animal subcategories; therefore values are assigned at the national scale for the main cattle categories (dairy and non-dairy cattle). When it was assumed that these parameters were uncorrelated at the regional scale, the overall uncertainties were reduced to 20 and 48% for enteric fermentation and manure management, respectively, and assuming that parameters were uncorrelated at the animal subcategory scale reduced uncertainties to 13 and 41% for enteric fermentation and manure management, respectively. When the uncertainty is assigned at the most disaggregated level, even doubling the uncertainty of key parameters such as Ym and Cfi, only increased the national uncertainties to 22 and 52% for enteric fermentation and manure management, respectively. The current analysis demonstrated the importance of obtaining parameters specific to regions and animal subcategories in order to estimate GHG emissions more accurately and to reduce the uncertainties in agricultural GHG inventories. It also showed that assumptions made in the calculation of uncertainties can have a large influence on the uncertainty estimates.

The viability of commercial potato production is influenced by spatial and temporal variability in soils and agroclimate, and the availability of water resources where supplementary irrigation is required. Soil characteristics and agroclimatic conditions greatly influence the cultivar choice, agronomic husbandry practices and the economics of production. Using the latest (UKCP09) scenarios of climate change for the UK, the present paper describes a methodology using pedo-climatic functions and a geographical information system (GIS) to model and map current and future land suitability for potato production in England and Wales. The outputs identify regions where rainfed production is likely to become limiting and where future irrigated production would be constrained due to shortages in water availability. The results suggest that by the 2050s, the area of land that is currently well or moderately suited for rainfed production would decline by 88 and 74%, respectively, under the ‘most likely’ climate projections for the low emissions scenario and by 95 and 86%, respectively, for the high emissions scenario, owing to increased likelihood of dry conditions. In many areas, rainfed production would become increasingly risky. However, with supplementary irrigation, c. 0·85 of the total arable land in central and eastern England would remain suitable for production, although most of this is in catchments where water resources are already over-licensed and/or over-abstracted; the expansion of irrigated cropping is thus likely to be constrained by water availability. The increase in the volume of water required due to the switch from rainfed- to irrigated-potato cropping is likely to be much greater than the incremental increase in water demand solely on irrigated potatoes. The implications of climate change on the potato industry, the adaptation options and responses available, and the uncertainty associated with the land suitability projections, are discussed.

The present paper compares standard and novel methods for analysing aggregated patterns of plant death in designed field experiments; these methods include binomial (BN), beta-binomial (BBN), logistic-normal-binomial (LNB), BN models with random blocks, BN models with smooth-scale spatial components and principal coordinates of neighbour matrices (PCNM). PCNM is a relatively new technique used in ecology to determine how much observed variability can be explained by spatial and environmental variables, and has not yet been applied to agricultural studies. The survival data of two pasture species, collected from a designed field experiment that was replicated at multiple locations, were used. First, the occurrence of overdispersion was tested using the BN and BBN distributions. Goodness-of-fit tests proved that the BBN model provided a better description (better fit) of the observed data in some cases than did the BN distribution, indicating overdispersion was present. When overdispersion was not present, the BN distribution was adequate to describe the data, and the use of the BBN distribution was superfluous. It is then shown that the PCNM approach, the BN model with smooth-scale spatial components and the LNB model were able to account for some of the variation as spatial variability, thus reducing the species effect compared with that explained under the standard BN model. The amount of variation among species according to the BN model and the BN model with random blocks was similar. Therefore, it is argued that the novel PCNM approach warrants further testing when exploring the spatial variability in designed experiments in agriculture and using LNB, PCNM and BN with smooth-scale spatial components may provide better predictions of species effects than do other, more conventional, approaches.

In wheat, the photothermal quotient (Q, the ratio between mean incident solar radiation and mean temperature is greater than 4·5°C in the 30 days preceding anthesis), is a good estimator of grain number/m2 (GN) and of yield. Previous investigations have not analysed in depth whether the responses of GN to Q differ between wheat cultivars, or what is the cause of the eventual variation. In the present work, the results of field experiments carried out between 1994 and 2001 in various locations were used to test the following hypotheses: (i) the responses of GN to Q differ between wheat cultivars; (ii) these differences are caused by differences in the spike fertility index (GN/g spike dry weight/m2 at the beginning of grain filling (SDW)). The responses of GN to Q were compared for five wheat cultivars (four bread wheats and one durum wheat) and it was found that with Q values above 0·3 MJ/m2/d°C, all responses of GN to Q were linear, positive and parallel. A method was then proposed to obtain cultivar-specific GN from a common relationship between GN and Q. This method would facilitate GN estimation in crops with changes in sowing dates, sites or years, starting from data of potential GN and yield that is relatively easy to obtain. Differences among cultivars in response to Q were due to differences in GN response at SDW. Similar SDW values produced different GN, depending on the spike fertility index of each cultivar. The cultivars did not differ in their responses of SDW to Q. The association between spike fertility index and SDW was strongly negative in bread wheat. At lower levels of Q or SDW, the spike fertility index increased in all cultivars, at least when changes in SDW or Q were caused mainly by intercepted solar radiation, but the present results demonstrate that differences between cultivars also exist in this relationship.

Coating barley seeds with free and immobilized alkaline phosphatase was investigated as a potential means to enhance plant utilization of accumulated soil phosphorus (P). Two coating techniques were studied: film-coating and pelleting. The highest phosphatase activity retention in the coating layer, ranging from 0·48 to 0·67, was observed when seeds were film-coated with phosphatase–polyresorcinol complex (PPC). The germination of seeds film-coated or pelleted with alkaline phosphatase ranged from 0·84 to 0·97 or 0·14 to 0·25, respectively. Low germination of the pelleted seeds was attributed to freezing the seeds in liquid nitrogen (N) for the layer coating formation. Pelleted seeds were not used in the remainder of the studies. Under pot culture conditions, an increase in the soil inorganic P was detected when the seeds were film-coated with phosphatase. Moreover, the film-coating significantly increased the P uptake by plants (between 25 and 31% after 35 days after planting (DAP)). The present study showed that the seed film-coating with free and immobilized phosphatase increased the phosphatase activity in the rhizosphere and the P uptake by plants.

A cropping system is the consequence of environmental and socio-economic conditions that determine the intensity of agricultural land use. Accurate information on regional land use intensity and changes in land use intensity is important for food security and sustainable resource management in China. Therefore, a better understanding of the spatial and temporal changes in arable land use intensity (ALUI) based on the cropping system used is essential to comprehend the changes in land use and the sustainability of the food system. The purpose of the present study was to investigate the spatial difference in ALUI and how it has changed in China by comparing data on cropping systems from 1985 and 2005. The basic cropping system data were acquired from the 1985 reference book and the 2005 national land use investigation. The ALUI was defined by the application of inputs (irrigation water and fertilizer) to arable land and the duration of disturbances (the duration of cultivation and the frequency of cropping), and it was calculated using the information entropy approach at the cropping region scale (cropping region being defined by the geographical and climatic conditions at the beginning of the 1980s). Spatial and temporal changes in the ALUI in China over the past two decades were observed and analysed. The results indicated a clear pattern in ALUI, increasing from the north to the south in 2005. Furthermore, the ALUI significantly increased after the 1980s, but the rate of increase was lower in the south than in the north. The most intensive land use in 1985 was in the area of the lower reach of the Yangtze and Huai Rivers, and it expanded northwards towards the Huang-Huai-Hai plain in 2005. The large increase in intensity in the northern single-cropping regions was strongly associated with a rapid increase in inputs and longer duration of cultivation. Decreases in duration of cultivation and planting area helped slow the ALUI increase in multiple cropping regions, which were concentrated in coastal and economically developed regions where more fertile soil and suitable climates existed, allowing the growth of multiple crops. These results suggested that a decrease in the planting area and a slow increase in the ALUI in the lower reaches of the Yangtze River, South China, Southeast China and Northeast China should be of concern, but land use in some western regions should maintain the land production capacity to build sustainable cropping. In the future, it will be necessary to produce more food in a more sustainable way.

Selection index theory was used to model the effects of methane (CH4) production in the breeding objective on genetic responses in Scottish Blackface sheep in hill production systems in the UK. A range of economic values (EVs) were assumed for CH4 production calculated from possible carbon prices (£/t CO2 equivalent (CO2-e)). The implicit price of carbon required for maintenance of CH4 levels or to reduce CH4 production by 0·1 kg/head/yr in a hill flock was calculated. The predicted genetic changes in CH4 production from current selection programmes that have an implicit methane EV of zero were calculated. Correlations between production traits and CH4 production were sampled from assumed normal distributions, as these correlations are currently unknown. Methane emissions are likely to increase at a rate of c. 3 kg CO2-e/ewe/yr as a result of using current industry selection indices in hill sheep farming systems in the UK. Breeding objectives for more productive hill sheep include reducing lamb losses and rearing more, heavier lambs. By placing a cost on carbon emissions to halt the genetic increase in methane, heavy penalties will be incurred by farmers in terms of reduced productivity. This amounts to £6/ewe/yr or a 5% discounted loss of £2851 per 100 ewe flock over a 10-year selection horizon. If the correlations between production traits and CH4 are positive (as expected) then an implicit carbon price of c. £272/t CO2-e is required for no genetic increase in CH4 production if methane is not measured and c. £50/t CO2-e if methane could be measured. Achievement of government targets for the whole economy of a 20% reduction in greenhouse gases (GHGs) over a 30-year period would require carbon prices (/t CO2-e) of £1396 (indirect selection) or £296 (direct selection) for the sheep industry to achieve a 20% reduction entirely via a genetic change of c. –0·1 kg methane/head/yr. These carbon prices are placed in the context of possible government policies. A combination of genetic and non-genetic measures will probably be required for cost-effective reduction in methane production to meet government targets.

At high northern latitudes, growing seasons are short with long days. In these conditions, tillering is an unwanted trait in barley (Hordeum vulgare L.), because the grains on tillers develop later than those on the main stem and are often harvested before they are fully mature, leading to reductions in overall quality. Hence, the uniculm growth habit has been considered an interesting option for boreal barley production. The aim of the present study was to determine the differences in the yield formation of conventional tillering and uniculm barley, using two pairs of near-isogenic lines and two controls. Uniculm and conventional tillering barley were grown in three experiments conducted at Suitia Experimental Farm, University Helsinki, Finland during 1999–2001. Samples were collected frequently to monitor the biomass and leaf area accumulation. Water-soluble carbohydrate content was analysed at anthesis and at maturity in different plant parts. At maturity, the numbers of spikes/plant and grains/spike were calculated and grain yield weighed. The grain yield of the uniculm barleys was stable over these growing seasons, but it was only half that of the conventional barley cultivars due to the absence of spike-bearing tillers, lower spike grain number and spike weight. In addition, the ability to transport photosynthesized carbohydrates to grains may have been reduced. Thus, it seems that uniculm barleys do not provide further improvement in barley yield.

The relationships of normalized water index three (NWI-3) and canopy temperature (CT) with grain yield in north-west Mexico were determined in a set of wheat lines planted in multi-location yield trials. Advanced wheat lines developed by The International Maize and Wheat Improvement Centre (CIMMYT) were included and tested internationally in the trials including the 24th Elite Spring Wheat Yield Trial (ESWYT), the 11th Semi-Arid Wheat Yield Trial (SAWYT) and the 11th High Temperature Wheat Yield Trial (HTWYT). In north-west Mexico, NWI-3, CT and grain yield were determined in three growing seasons (2006, 2007 and 2008) and three environments (well irrigated, water-stressed and high-temperature), while grain yield was measured at international locations in the same advanced lines of the 24th ESWYT, the 11th SAWYT and the 11th HTWYT . The CIMMYT database was used to obtain grain yield from worldwide nurseries. The mean grain yield ranged from 0·8 to 12·7 t/ha for the 24th ESWYT (59 international sites), from 0·6 to 8·2 t/ha for the 11th SAWYT (28 international sites) and from 0·4 to 7·5 t/ha for the 11th HTWYT (26 international sites). NWI-3 and CT for the advanced lines in the three yield trials measured in north-west Mexico in distinct environments showed significant associations with the grain yield from a few international locations (0·12–0·23 of sites). Locations from Central Asia and North Africa had the best associations with NWI-3 and CT. The lack of more associations may be due to either an interaction of other factors (low rainfall and limited irrigations), which affected yield performance, or few of the advanced lines were well adapted to local growing conditions at each testing site, or a combination of these factors. The present results indicate that NWI-3 and CT have limited potential to predict yield performance at international sites.

The impact of projected regional climate change on the migration of cabbage stem weevil (Ceutorhynchus pallidactylus) to oilseed rape crops in the Grand Duchy of Luxembourg is evaluated for past and future time spans. Several threshold-based statistical models for the emergence and the main migration of C. pallidactylus were chosen from the literature and combined with selected regional climate change projections of the EU ENSEMBLES project. Additionally, a simple degree-day based model was used to assess the plant development under expected climate change conditions. An earlier onset as well as a prolongation of the possible emergence times and the main migration periods was detected. The onset of stem elongation of oilseed rape was predicted to occur 3·0 days earlier per decade, while emergence of C. pallidactylus was expected to occur between 3·0 and 3·3 days earlier per decade. The main migration period of the weevil to the field may start 2·0 days earlier per decade under future climate conditions. Additionally, the time span of possible migration is prolonged for about 30 days under projected future climate conditions.

A detailed study of nitrogen use efficiency (NUE) and its components in three cultivars of winter wheat, Hereward, Rialto and Riband was undertaken in cultivar trials conducted in Northern Ireland in 1998 and 1999. Yield, grain N concentration, harvest index (HI), nitrogen harvest index (NHI), N uptake efficiency (NUpE), total N uptake, grain N off-take, N utilization efficiency (NUtE) and NUE itself all showed significant variation between sites. Cvars Hereward and Rialto had similar mean values across all the sites for many of the characteristics, with Riband usually differing. In all but one characteristic, grain N concentration, the responses of the three cultivars varied significantly from trial to trial and this, along with the substantial variation between sites, indicates that genetic control of the characteristics is partial. The amount of N applied as fertilizer accounted for little of the variation among the trials with weak associations for NUpE, which decreased, and grain yield, which increased with increasing fertilizer N. Neither grain yield nor NUE was associated with the amount of N taken up by the crop, but grain N concentration increased and NUtE decreased significantly. HI and NHI differed significantly among the cultivars, diverging at higher N uptakes, with Hereward and Rialto being similar and distinctly different from Riband. Grain yield was only weakly associated with NUpE but was strongly and positively associated with NUtE and NUE. The strong negative association between NUtE and NUpE highlights the potential and the urgency of understanding factors influencing uptake of nitrogen by crops. The extent of the non-genetic, i.e. environmental and management, variation in the characteristics, along with the relative similarity of the cultivar means, throws up a challenge to plant breeders, agronomists and researchers wishing to improve NUE genetically and through management. As with yield and other characteristics, a large number of trials will be required to identify consistent differences in NUE among cultivars. Thus, while mechanisms underlying NUE, NUpE and NUtE need to be understood, the possibility of using the HGCA UK Recommended List database to investigate NUE and identify cultivars with improved NUE should also be considered. Since in each of the HGCA trials cultivars have access to the same available N, and since grain yield=available N×NUE, grain yield itself is a surrogate for the NUE of cultivars. Grain N concentration is only determined in a few cultivars at present but could be used as an indicator of optimal N availability in individual trials, allowing variation in NUE of cultivars in response to agro-ecological factors on NUE to be studied.